r/Powerlines

I'm a structural engineer working on a transmission line project overseas. The project has a dedicated national transmission tower design code — published by the local power utility itself, specifically for this type of structure. Our entire design report is based on it.

Then comes the review.

1. The utility's own tower code? Not good enough.

The reviewer rejected our load combinations, which follow the mandatory transmission tower standard published by the very utility that owns this infrastructure. Their reasoning: we should apply the general building steel structure code instead.

So the power company's own engineers spent years writing a specialized code for transmission towers, the contract specifies it as governing, and the reviewer decides a building code takes precedence.

I don't know what to call that other than not reading the project documents.

2. Seismic analysis on a lattice tower. Yes, really.

We're talking about a relatively light 33 kV distribution-level tower here.

We were asked to perform quantitative seismic calculations. For a transmission tower.

Everyone in the transmission line industry knows that wind — or ice — not seismic, governs lattice tower design in virtually all cases. Towers are lightweight, have very short natural periods, and carry no significant mass at height. IEC, ASCE, CIGRE — every major international standard treats seismic as a secondary check, often qualitative. The reviewer cited a general building seismic clause and asked us to apply it wholesale.

3. P-delta analysis. On a pin-jointed truss.

The reviewer requested second-order P-Δ analysis, citing a building frame stability clause.

P-Δ is a concern for moment-resisting frames — structures where lateral loads create significant secondary moments due to sway. A self-supporting lattice tower with triangulated geometry and pinned connections has completely different stability behavior.

The structure they're asking me to treat like a high-rise is a pile of angles and bolts in a triangulated pattern that's been used safely for over 100 years without P-Δ checks. If P-Δ were relevant to lattice towers, ASCE 10 would say so. It doesn't.

4. A single-circuit tower — reviewed as if it were double-circuit. With three crossarms drawn right there on the drawing.

The broken wire load case is fundamental: you design for the tension imbalance caused by one wire snapping. Standard stuff.

The reviewer asked us to consider two wires breaking simultaneously.

Here's the thing: on a double-circuit tower, each phase position carries two wires (one per circuit), so losing one still leaves the other — hence some codes require a two-wire broken case. That logic makes sense. For a double-circuit tower.

Ours is single-circuit. Three crossarms, three phases, one wire each. It is drawn on every single structural drawing.

Three crossarms. You can count them. I counted them. Apparently the reviewer did not.

So either they looked at three crossarms and somehow concluded "double circuit," or they copy-pasted a broken wire requirement from a double-circuit checklist without glancing at the actual tower configuration.

The drawing title says single-circuit. The crossarm count says single-circuit. Physics says single-circuit.

We were asked to snap a wire that doesn't exist.

5. ASCE 10 isn't enough — they want a second pass per the building code.

ASCE 10 is the international standard specifically written for latticed steel transmission structures. It covers member design, slenderness, eccentricity, block shear — everything specific to angle members in tower panels. It exists precisely because general building codes don't handle this stuff well.

The reviewer wants us to re-verify every member against the general building steel code on top of that. Not because there's a known discrepancy. Not because ASCE 10 has a gap. Just because.

It's like asking someone who passed their medical board exams to also sit the veterinary licensing exam, just to be safe.

The frustrating thing isn't the workload — it's the asymmetry. Every single comment requires you to first establish which universe we're operating in before you can even respond to the technical substance. You end up writing a standards lecture for every line of the Comment Resolution Sheet.

You're not defending your calculations. You're defending the existence of your entire discipline.

And the reviewer can always send it back.

Has anyone else dealt with reviewers who are clearly from a buildings background trying to review transmission infrastructure? How do you get the conversation back on track without it turning into a war?